1. Field of the Invention
The present invention relates to a novel fulgimide compound having photochromic action, to a composition containing the same compound and to the use thereof. More specifically, the invention relates to a novel fulgimide compound having excellent durability which changes from a colorless state into a colored state upon the action of light that contains ultraviolet rays such as of the sun light or the mercury lamps, the change being reversible, to a composition containing the same compound and to the use thereof.
2. Description of the Prior Art
Photochromism is a phenomenon which is drawing attention in these several years and is a reversible action exhibited by certain compounds. That is, a compound quickly changes its color when it is irradiated with the sun light or the light containing ultraviolet rays such as of a mercury lamp and returns to the original color when it is no longer irradiated with the light and is placed in a dark place. The compound having this property is called photochromic compound, and compounds having various structures have heretofore been synthesized and proposed without, however, any common skeleton among their structures.
Under such circumstances, a fulgide compound or a fulgimide compound disclosed in Japanese Laid-Open Patent Publication No. 28154/1990 and represented by the following general formula ##STR4## exhibits no color and remains stable in a general state but readily develops color upon irradiation with the sun light or ultraviolet rays, returns to the colorless state when it is no longer irradiated with the light, and is, hence, a compound having excellent photochromic property making it possible to repeat these changes in color maintaining good durability. In the fulgide compound or fulgimide compound, X ##STR5## stands for an aromatic hydrocarbon group or an unsaturated heterocyclic group, and R.sup.1' stands for a hydrocarbon group or a heterocyclic group. Moreover, Y' stands for an oxygen atom, an imide group, or a group in which a hydrogen atom of the imide group is substituted by a group to which is bonded an electron-releasing group of an alkyl group or an aryl group or to which is bonded an electron-withdrawing group of a cyano group or an alkoxycarbonyl group via an alkylene group or an alkylidene group. Furthermore, ##STR6## represents a norbornylidene group or an adamantylidene group which may have a substituent.
It has been considered that the fulgimide compound which has a rigid cage-like adamantylidene group or a norbornylidene group without distortion, weakens a single bond that constitutes a part of a six-membered ring, facilitates electron-cyclic ring cleavage upon irradiation with the light containing ultraviolet rays, and, as a result, assumes a color-producing form. As a maximum absorption wavelength is lengthened, however, these compounds develop a defect in that they have already been exhibiting yellowish color (hereinafter often referred to as initial coloring) before they are being irradiated with ultraviolet rays. When these compounds are used for a photochromic lens or the like, therefore, the lens at first exhibits a yellow color.
In such circumstances, therefore, it has been urged to develop a photochromic compound suppressing the initial coloring despite a maximum absorption wavelength is lengthened.